Processes of fabricating a liquid crystal display (LCD) screen mainly include a process of a thin film transistor array substrate, a process of a color filter layer, an assembling process of a liquid crystal (LC) cell, an assembling process of a LC module (LCM), and so on. Among the foregoing processes, the assembling process of the LCM is a process in which a metal frame, a LCD panel, and a backlight module are assembled, and after assembling the LCM, the LCD screen is completely manufactured. More specifically, in the assembling process of the LCM, the LC cell is overlaid on the backlight module, through interlocking of the metal frame and a mold frame of the backlight module, folding a printed circuit board (PCB) to a backside of the mold frame, and then electrically connected to the PCB, so as to finish the assembling processes of the LCD panel and the backlight module.
In regard to the LCD panel of the LCD, it is not a self-luminescent display element, and thus requires a light source provided by the backlight module. In other words, the backlight module provides the required brightness, uniformity of brightness, and the visual angle (the aligning angle of the emitting light) for displaying pictures. With regard to mechanical properties, the backlight module must be thin, light, and tolerant to shock. The properties of the backlight module directly influence the quality of the LCD, and thus, the backlight module is a very important component.
The backlight module typically comprises a diffuser, a light guide plate, a plurality of backlight sources, and a chassis. The light guide plate is used for guiding light in a planar surface to ensure uniform brightness of the LCD panel. The backlight sources must be highly bright, long-lasting, and so on, and the backlight sources are mainly cold cathode fluorescent lamps (CCFL). When the backlight module is thinner, the shapes of the backlight sources more easily cause irregularity and shadows on the LCD screen because the backlight sources are arranged directly under the light guide plate. The common solution is to install a diffuser or adjust the shape of the diffuser to scatter the light passing through the light guide plate, thus eliminating the shadows of the backlight sources and making the brightness of the screen more uniform. As for the chassis, it is used as a reflector, and can prevent the light emitting by the backlight sources from leaking out, and increase the utility efficiency of light.
However, many problems exist in the assembling process of the LCM in the prior art. For example, reference is made to FIG. 1, which illustrates a schematic diagram showing the engaging structure of the backlight module in the prior art. The engaging structure 100 of the backlight module in the prior art comprises the chassis 101 and the mold frame 111. The chassis 101 may be made of aluminum and comprises a bottom plate 103 and a first side wall 105 disposed on the bottom plate 103 and surrounding the edge thereof for defining a space 107. The mold frame 111, which can be integrally formed from plastic with mold and be mounted in the space 107 of the chassis 101, comprises a frame margin 113 and a second side wall 115 disposed beneath the frame margin 113 and surrounding an outer edge thereof.
Reference is made to FIG. 2, which illustrates a cross-section of part of the backlight module in the prior art. Because the mold frame 111 on a side of the backlight sources 121 has no positioning structure, the mold frame 111 may shift and even generate a twisted displacement. For example, the mold frame 111 may shrink to a side of the LCD panel (not shown) and influence the LCD panel, the films 123 such as the diffuser and the light guide plate may warp, the backlight sources 121 may shift, and drawbacks such as a light leak of the backlight module or luminescent lines occurring on the LCD panel may even result. In addition, the driving integrated circuit (IC) 125 connects to the LCD panel (not shown) with a tape carrier package (TCP) technique. The chassis 101 is typically made of aluminum. During the assembling process, the uneven edge 102 of the chassis 101 may easily scrape the driving IC 125 on the side of the backlight sources 121.